Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1987 Oldsmobile ToronadoFACTORY OEM SERVICE PROCEDURE
Code B556, Odometer (Ee) Prom Error
Code B556 indicates that the EE PROM, which records elapsed odometer mileage, is not being read by the BCM. Usually along with Code B556, "ERROR" will be displayed in the odometer display.
- Check for proper EE PROM installation.
- If PROM is properly installed, no bent pins, then replace EE PROM.NOTE: New EE PROM will have to be adjusted to the current mileage, proper VIN, and option content by the AC-DELCO repair station.
- If a properly installed EE PROM continues to display "ERROR", replace BCM.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.